Process of roasting ores.



No. 808,361. PATENTED DEC. 26, 1905. H. HAAS.

PROCESS OF ROASTING ORES.

APPLICATION FILED AUG.3.1905.

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PROCESS OF ROASTING ORES.

APPLICATION FILED AUG. 3. 1905.

- L N @g @m UNITED STATES PATENT OFFICE.

Specification of Letters Patent.

{Patented Dec. 26, 1905.

Application filed August 3, 1905- Serial No. 272,618.

To all whom, it may concern.-

Be it known that LHERBERT HAAS,a citizen of the Republic of Switzerland, residing at San Francisco, in the county of San Francisco and State of California, have invented certain new and useful Improvements in Processes of Roasting Ores, of which the following is a specification.

This invention relates to an improved process of roasting ores, the object of the invention being to provide a process by which ores can be sufficiently roasted in a much shorter time than has heretofore been known to metallurgy without prohibitive losses of values, by which the ores will be fritted together into such form that they can be smelted direct in the blast-furnace without previously briqueting, the sintered character of the material greatly increasing the speed of the smelting process, by which at the same time sulfur dioXid and sulfuric-acid anhydrid will be produced in sufliciently concentrated form to be used for the manufacture of sulfuric acid.

In the accompanying drawings, Figure 1 is a broken end view of an apparatus adapted for use with my improved process. Fig. 2 is a detail sectional view showing the end of the shell. Fig. 3 is a top plan view of said shell. Fig. 4 is a broken side view of the apparatus, the upper portion being omitted.

Referring to the drawings, 1 represents a semicylindrical shell, ofsheet-steel, cast-iron, or steel, in which the ores are placed. The trunnions 2 of said shell rest in pillow-blocks 3, supported upon stands 4, secured by bolts to an appropriate fastening. Each end piece 5, closing the semicylindrical shell 1, the corresponding sprocket-wheel 6, and the corresponding shaft or trunnion2 are all cast in one piece, which is securely bolted to the semicircular ang1eiron 8, which is riveted to the desulfurizing shell 1 but between the angleiron and the endpiece is interposed a steel plate 9, semicircular in form to correspond with the contour of the angle-iron and provided with asbestos packing 10 between said plate and the angle-iron, thus making an airtight joint. In each end of the shell is inserted a plate 11 at such an angle as to facilitate the removal of the ore after desulfurization, the space 12 between the plate and the end of the shell serving as a wind-box in which the pressure of the air blown into said box is equalized and made uniform, said air passing into a twyer-boX 13, of cast-iron or cast-steel, bolted to the bottom of the shell, the ends of the twyer-boX being bolted to the plates 11 around openings therein. The cross-sectional form of this twyer-boX is triangular with a slight rounding on its apeX. The air is forced into said wind-b oXes through delivery-pipes 14, the blast passing to the twyer-boX and then passing through small openings 15 in said twyer-boX into the shell in which'it is mixed with the ore. The air is delivered to the desulfurizer by means of a metallic flexible tube 16, provided with an air-gate 17 and a pressure-gage 18 to regulate the quantity of air so delivered. This allows the turning of the vessel Without disconneoting the air connections or requiring a specially-constructed movable arm.

19 represents intermediate angle-irons used to strengthen the vessel and maintain its form. The roaster is rotated on its trunnions by a sprocket -wheel 6 and chain 20, driven from a motor or any other suitable source of power.

21 represents a flue into which the fumes are conducted from the shell by means of a pipe 22, leading from a hood 23, which is arranged over the shell, said hood being provided with a movable door 24, covering the whole of one side, by which the ore can be charged into the desulfurizingshell, and movable lid 25 on the other side to prevent accident to the hood when the roasted product isbeing dumped.

The process is as follows: A small fire having been started over the twyers, the shell is filled with crushed ores. A light blast is started and continues for an hour. The blast is then gradually increased, and when chemical action takes place the blast is again decreased. Sulfur dioxid and sulfuric acid anhydrid and other metallic oXids are driven off. When the ore has been roasted sufficiently, the shell is tilted, discharging the roasted product, and is recharged for repeating the operation.

t is found that by this process the ores are fritted together into such form that they can be smelted direct in the blast-furnace without previous briqueting, thus greatly economizing in the process of extracting the met als. The sintered form of the material greatly increases the speed of the smelting; but the most important feature of the invention is the rapidity of roasting the ore without losing any material amount of values.

The sulfur gases for making sulfuric acid are produced without any additional expenditure. By eoonomizing in these three particulars the invention causes a great saving in the process of reducing metals from ores.

By introducing steam with the air into the ore masses ores with a large percentage of zinc sulfid are decomposed, the steam forming with the zinc sulfid metallic zinc and hydrogen sulfid. In this modified process the steam is not introduced until the sulfurous-acid fumes are diminishing, showing that the readilydecomposed sulfidssuch as copper, iron, and lead sulfids-are readily converted into oxids.

As a modification of this process and as an other way in which this apparatus can be used there can be commingled with the mineral sulfids before charging the same into the desulfurizing-shell any suitable fiuxsuch as lime, hematite, or quartz-in the proportions required for the smelting charge in blast-furnace or reverberatory smelting. Then upon carrying out the above process the resulting product will be a compound of the roasted ore and of the flux thoroughly commingled and fritted together into convenient blocks, the intermingling of the ore and flux being so close that the blastfurnace or reverberatory process is operated with very great advantage and economy. It is to be well understood that the addition of these fluxes is by no means an essential part of the process, but is only a further development of the same, which may or may not be resorted to as may be desired.

The form of the shell is an important feature of this apparatus. In order to carry out this process efficiently, it is necessary that the layer of ore should be not too deep to prevent the sulfur gases escaping to the sur face. Unless the shell is made somewhat shallow the sulfuric acid generated at the bottom of the layer cannot pass quickly enough to the surface. The semicylindrical form with the twyer at the bottom extending the whole length is therefore necessary to efiect the above result. For this reason also it is very essential that the twyer should have a very large number of openings discharging the air simultaneously at all points of the bottom of the shell instead of as heretofore discharging the air at a single point or at a few central points. With a construction of the latter character the heat is concentrated around the mouth of the twyer, causing a smelting heat at that point and insufficient heat at other points of the shell.

By means of my apparatus a heat sufficient to drive off the first part of the sulfur can be generated without its being high enough to smelt the ore at any point.

I claim" 1. The process of roasting ores which consists of bringing them to the point of ignition, and supplying a light blast of air evenly distributed throughout the whole mass for the purpose of maintaining combustion thereof, and creating a sintered agglomeration, said blast being sufficiently light, and being continued for a sufficient time, to drive off and oxidize only the more easilyseparable molecules of sulfur, or other metalloids, maintaining the heat below the smelting-point, and then increasing the blast to separate from the residue the less easily separable molecules of sulfur, continuing to increase the blast as required for the complete separation of the sulfur and then decreasing the blast in propor tion to the amount of air decreasingly required to combine with the residual sulfur or other metalloids, substantially as described.

2. The process of roasting ores and producing a smelting charge which consists in mixing with the ores a suitable fiux in suitable proportions, creating a sintered agglomeration by raising the ore-flux mixture to the point of ignition of the sulfur or other metal loids, subjecting the same when so ignited to a light blast of air evenly distributed throughout the whole mass, continuing said blast for a sufficient time and with sufficient strength only to drive off and oxidize the more easily separable metalloid molecules, while maintaining'the heat below a smelting temperature, and, when the more easily separable metalloid molecules have been driven of, in creasing the blast to drive off the less easily separable metalloid molecules, maintaining the air-supply in proportion to the amount required for combustion, and decreasing the air-supply when necessary as the amount of sulfur and other metalloids remaining to be oxidized decreases, substantially as described.

In witness whereof I have hereunto set my hand in the presence of two subscribing witnesses.

HERBERT HAAS.

Witnesses:

EDITH WOODWARD, BESSIE GORFINKEL. 

